Method for making sulfur-oil slurry for pipeline transportation



Oct. 6, 1970 BUTANE ADDITIVE W. H. THOMPSON METHOD FOR MAKING SULFUR-OIL SLURRY FOR PIPELINE TRANSPORTATION Filed Dec. 18, 1968 COM PRESSOR I a CONDENSER FLASHER 23 @SETTLER SULFUR-OIL SLURRY SULFUR THICKENED 27 SLURRY SULFUR-SLURRY lNVENTORSf H. THo soN E. YOUNG THEIR AGENT United States Patent Ofice 3,532,389 Patented Oct. 6, 1970 3,532,389 METHOD FOR MAKING SULFUR-OIL SLURRY FOR PIPELINE TRANSPORTATION William H. Thompson, St. Louis, Mo., and Eldred E. Young, Concord, Califi, assignors to Shell Oil Company, New York, N.Y., a corporation of Delaware Filed Dec. 18, 1968, Ser. No. 784,616 Int. Cl. B65g 53/ 30 US. Cl. 302-66 5 Claims ABSTRACT OF THE DISCLOSURE An improved method of making sulfur-oil slurries for pipeline transportation by evaporation cooling of said slurries prior to introducing said slurries into the pipeline.

The present invention relates to an improved method of making sulfur-oil slurries for pipeline transportation by cooling said slurries prior to injecting said slurries into a pipeline by evaporation cooling with a volatile low molecular weight hydrocarbon such as an aliphatic hydrocarbon having less than 6 carbon atoms.

BACKGROUND OF THE INVENTION The transportation of sulfur neat or as a water or oil slurry in pipelines is well known in the art as noted by reference to US. Pats. 2,798,772; 2,917,345 or 2,947,578 or as described in Pipeline Industry, June 1967, pages 58-60. In making the sulfur into a sulfur-hydrocarbon slurry, the sulfur is generally sprayed in molten form into either water or a hydrocarbon to form a slurry suitable for transportation through a pipeline. Formation of a stable slurry wherein the sulfur does not undergo any undesirable change or the slurry does not exhibit a tendency to wide variation in viscosity is essential to the process in addition to other problems which may be encountered during and after transportation of the slurry through a pipeline. Thus, agglomeration and separation of the sulfur from the carrier fluid, plating, depositing or coating of the sulfur on pipeline walls causing plugging of the pipeline, corrosion, viscosity changes due to pressure and temperature variations requiring greater pumping power which increases operation costs, etc., are only a few of the problems normally encountered in making sulfur-liquid hydrocarbon slurries for transportation through pipelines.

Although the above are serious problems for consideration in transporting sulfur through pipelines, nevertheless the transportation of sulfur in slurry form through pipelines can be made to be an effective, attractive and economic means of sulfur transportation, particularly since sulfur is recovered or obtained from isolated, remote and inaccessible areas, and must be transported to desired accessible areas. As noted above, a number of methods have been proposed for making sulfur slurries for pipeline transportation such as by injecting molten sulfur into water or a liquid hydrocarbon thereby forming a sulfur slurry and thereafter injecting the slurry into a pipeline for tansportation to a terminal station. Known methods for making sulfur slurries suitable for transporting through pipelines generally do not overcome the agglomeration, deposition, sticking, coating and/or plugging problems described above. Also, it is essential that in order to avoid the sticking of sulfur to pipeline walls and plugging of the pipeilne, that the slurry when injected into the pipeline be at a temperature of below 150 F. and preferably around 120 F. or lower. Since the molten sulfur is generally at around 240 to 300 F. or higher for injection into a hydrocarbon carrier, the slurry formed is substantially above the temperature required for pipeline injec tion and therefore must be cooled, preferably to at least F. Therefore, slurrying sulfur in oil and cooling it effectively for pipeline injection and transportation is an essential feature of the technology of sulfur-oil slurry making and cooling. Conventional cooling such as allowing the slurry to cool on standing is time consuming and costly and other means such as surface heat exchange is also costly and prone to fouling and plugging.

An object of the present invention is to prepare sulfurliquid hydrocarbon slurries suitable for pipeline transportation.

Still another object of the present invention is to prepare sulfur-liquid hydrocarbon slurries which are resistant to agglomeration, deposition, sticking and plugging of equipment used in its manufacture and pipelines transporting said slurries to a terminal station.

Still another object of this invention is to prepare a sulfur-oil slurry in which the sulfur particles are essentially in spherical form and are resistant to attrition, separation and deposition and sticking to metal surfaces.

Still another object of the present invention is to prepare a sulfur-oil slurry for pipeline transportation such that it can be pumped at reduced pumping costs and requires a minimum of handling and is readily separated from the oil phase at the terminal end of the line.

Still another object of the present invention is to effectively cool sulfur-oil slurries to a temperature range suitable for injection into pipelines for transportation of the slurries to terminal stations.

Other objects will be apparent from the following description.

SUMMARY OF THE INVENTION It has now been discovered that sulfur-liquid hydrocarbon slurries for pipeline transportation can be effectively cooled and maintained below about F. and preferably around 120 F. or lower and made so that the sulfur is dispersed in the liquid hydrocarbon carrier in a stable form resistant to agglomeration, sticking and attrition by injecting molten sulfur into a suitable liquid hydrocarbon carrier ranging in viscosity from gasoline to a crude oil and preferably also adding to the carriers a small amount, preferably less than 20% based in the carrier of a vaporizable low molecular weight hydrocarbon such as an aliphatic hydrocarbon of less than 6 carbon atoms, e.g., propane, butane and pentane and mixtures thereof which on evaporation cools the sulfur-liquid hydrocarbon slurry to a temperature required for pipeline injection and transportation. Cooling the slurry by evaporation of the C or lower hydrocarbon from the slurry also concentrates the sulfur slurry which can contain from 2075% by volume of sulfur stably dispersed in the liquid hydrocarbon carrier which can range in viscosity from a light petroleum fraction such as liquefied petroleum gas (LPG), gasoline, kerosene, fuel oil, lube oil, petroleum distillates, condensates, crude oil and mixtures thereof. Preferred carriers are liquid petroleum containing at least 10% or higher of aromatics, preferably about 1580% aromatic enriched kerosene or oil condensate fractions or crude oil containing 1530% aromatics which include monoand polyaromatic hydrocarbons.

Although the addition of volatile low molecular hydrocarbons such as butane to liquid hydrocarbon carriers such as petroleum distillates, condensates or crude oil used for making sulfur slurries by direct injection of molten sulfur into a carrier effectively cools and concentration must be kept within critical limits of from about 5% to less than 20%. Higher concentrations of said volatile hydrocarbons, e.g., butane, have an adverse effect on shape, strength and size on sulfur particles required for pipeline transportation. Thus, the presence of 25% or more of a volatile hydrocarbon in a sulfur-oil slurry has been found to produce irregular sulfur particles 3 which are weak susceptible to attrition and the like. On the other hand it has been found that evaporation cooling of a sulfur-liquid hydrocarbon slurry with small amounts of butane and the like effectively cools the slurry and it has no undesirable effects with respect to size, shape and strength of the sulfur particles.

The volatile hydrocarbon, e.g., butane, can be added to, admixed with or injected into any suitable liquid hydrocarbon carrier, e.g., crude oil or fractions thereof, used in making sulfur slurries. Thus, the butane can be added separately to the carrier, e.g., crude oil, and fractions thereof and the molten sulfur is injected into such a mixture or the butane can be mixed with the crude oil and fractions thereof and the sulfur injected thereafter into the liquid hydrocarbon. After the desired amount of molten sulfur has been added the butane can be evaporated from the slurry by pressure adjustments so as to effectively cool and concentrate the sulfur slurry for injection into a pipeline for transportation to a terminal station without the danger of sulfur attrition of sulfur plugging of the line. The evaporated hydrocarbon (butane) can be recovered by compression and condensation and recycled and used again if desired.

BRIEF DESCRIPTION OF THE DRAWING The drawing illustrates the process of this invention.

Into spray or slurry vessel 26 is introduced oil via line 10.into which line can be also introduced additives via line 13 and the oil or oil-additive mixture is passed through pump 31 into valved lines 14 and/or 16, the latter of which meets recycle oil line 17. Into vessel 26 is also introduced molten sulfur via line 11, heat exchanger 25 and spray nozzle 33 which can be above or below the oil level. The vessel 26 into which the oil and molten sulfur is injected can contain a stirrer 32 so as to aid in mixing the sulfur and oil in vessel 26 which if necessary can be heated by suitable means such as by steam jacketing the vessel 26. A volatile hydrocarbon, e.g., butane, via line 12 and valved line 15 can be introduced into the valved oil lines 14, 16 and/or recycle oil line 17 and into vessel 26. After all of the molten sulfur has been added part of the volatile hydrocarbon (butane) is flashed off and removed via valved line 19 into compressor-condenser 30 and recycled, if desired, into vessel 26 via lines 12 and 15. The sulfur slurry is removed from vessel 26 via line 21 and pumped through pump 27 into a flasher 28 wherein the remainder of the volatile hydrocarbon (butane) is flashed off and removed via valved line and compressed and condensed in and reused as previously noted. The sulfur-oil slurry can be removed from the flasher via valved line 22 or the sulfur-oil slurry can be thickened by sending it via valved line 23 into a settler 29 wherein a thickened sulfur-oil slurry is removed via line 24 for pipeline injection and transportation and the oil recycled if desired via lines 18 and 17 into the slurry vessel 26. The slurries recovered from lines 22 and/ or 24 are cool enough for pipeline transportation so as to obviate the dangers of injecting hot slurries into a pipeline as described above.

PREFERRED EMBODIMENT OF THE INVENTION A preferred method for preparing a sulfur oil slurry for pipeline transportation comprises spraying molten sulfur (10-70%) via line 11 into a steam jacketed vessel 26 which contains crude oil added thereto via lines 10, 16 and 17 and additives added thereto via line 13, which inclnde asphaltenes or polar-containing natural petroleum products. Butane is introduced into the vessel 26 via lines 12, 16 and 17 in an amount of between 5% and 20% and the entire mixture is agitated until the slurry is homogeneous. After all of the molten sulfur has been added some butane is flashed off from the slurry vessel 26 by pressure control and removed via line 19 thereby cooling the sulfur-oil slurry from about 140 F. to about 100 F.

The partially cooled slurry leaves the slurry vessel 26 having a sulfur content of from about 12 to about 18% and is pumped via line 21 and pump 27 into flasher 28 where essentially all of the butane is flashed off and removed via line 20 and compressed and condensed in 30 and recycled into the oil line 15 and into slurry vessel 26 via line 14 through sulfur nozzle 33 or directly into the slurry vessel via line 17. The sulfur-oil slurry is concentrated due to removal of the butane to above 20% and generally between 20% and 30% and is removed from the flasher via line 22 at a temperature of around 70 F. Instead of using only one flasher 28 as shown in the drawing, a series of flashers can be used and the slurry can be used and the slurry can be cooled in stages. To obtain a more concentrated sulfur slurry the sulfur-oil slurry line 22 can be closed and the slurry is set to settler 29 via line 23 where the slurry is allowed to settle into an oil phase which is removed via line 18 and the oil recycled into slurry vessel 26 via lines 15, 16 and 17 or via lines 15, 10 and 14. The thickened sulfur slurry is removed from settler 29 via line 24 and has a sulfur concentration above 30% and preferably between about 35 and 60% by weight which can be pumped directly into a pipeline for transportation to a terminal station.

During the preparation of the sulfur-oil slurry in vessel 26, sulfur slurry improvement additives can be introduced in amounts of from 0.1% to 10% (0.5-5%) into the oil which aid in formation of spherical sulfur particles within the range of 20 to 800 microns and which impart to the slurry other benefits. The additives best suited for this purpose include asphaltenic additives which can be obtained from unrefined or refined crude oil and fractions thereof. By unrefined crude oil is meant any crude oil which has not been processed in a refinery. Thus, a crude oil may be used as it is removed from the ground, or it may be first processed in field units such as oil-water separators, degasers, etc. Although just how the asphaltenes function in the slurry mixture is not understood, it has been found that the asphaltenes prevent sulfur agglomeration, sticking and aid in the formation of spherical sulfur particles having dimensions of from 10 to 800 microns and preferably between and 700 microns.

The asphaltenes can be recovered from petroleum stocks by any suitable means such as described in the Journal of the Institute of Petroleum, February 1968, pages 50-53 and April 1968, pages 107-114 or as described in U.S. Pats. 3,206,388; 3,228,870; 3,153,623; 2,729,589; 3,368,- 876; 3,364,138; 3,206,388 and 3,275,076. The latter two base materials can be used per se as the asphaltene additive and carrier for the slurry. In other words high asphaltenic crudes or fractions thereof containing at least 1%. asphaltenes can be used both as the carrier and additive for the sulfur slurry. The asphaltenes, asphaltogenic acids and carboids and their method of recovery and separation from crudes and fractions thereof is also fully described in chapter 9' of the Sachanens book on The Chemical Constituents of Petroleum and includes petroleum resins, asphaltenes, asphaltogenic acids and their derivatives. Also, the asphaltenic materials described in U.S. Pats. 3,275,- 076; 3,284,340 or 3,336,146 can be used and they can be separated from petroleum by methods described in U.S. Pats. 3,364,138 and 3,368,876.

Instead of asphaltenes, natural surfactant components present in crude Oil can be used. The natural surfactants present in the crude oil include the natural polar-containing constituents present in crude oil such as the nitrogenoxygenand sulfur-containing materials and active hydrocarbons possessing surfactant properties and the materials can be added to the slurry of sulfur and liquid petroleum as described prior to or during the making of the slurry or these active surfactant materials can be injected when necessary in various places along the pipeline where indications are that the slurry might cause sulfur agglomeration, deposition, sticking or plugging of the line. Any plugging detection means known in the art can be used for this purpose. It has been noted that by adding or injecting into a slurry of the sulfur and liquid petroleum in which the sulfur content of the slurry can vary from about 10% to about 75% or higher, preferably between 30 and 70% sulfur, e.g., kerosene or oil condensate or crude oil, during or after the slurry preparation of from about 0.1 to 10% of an active surfactant material derived from crude oil, that these active surfactant materials not only prevent plugging of pipelines transporting said slurry but also preventing agglomeration of sulfur, sticking during the slurry preparation and deposition of sulfur on the walls of the pipelines and improves flow of the slurry and reduces pumping costs.

The preferred additive is asphaltene and it should be added to the oil first and the molten sulfur injected thereafter.

Oils, preferably crude oils rich in asphaltenes, can be used per se in making the sulfur slurry. Generally, the liquid petroleum carrier for the sulfur can be one ranging in viscosity from a light petroleum fraction such as liquefied petroleum gas (LPG), gasoline, kerosene, fuel oil, lube oil, petroleum distillates, condensates, crude oil and mixtures thereof. A typical crude suitable for making the sulfur slurry has the following properties shown in Tables A and B.

Tables A and B give the properties of oil suitable for sulfur slurry making the Tables 1-4 set forth the conditions for making sulfur-oil slurries in accordance with the process of the present invention.

TABLE A.PROPERTIES OF CANADIAN RANGELAND- TYPE CRUDE OIL Gravity, API 38. 7 SMS 150/62. Viscosity, GS: SMS 170/62.

60 F 6. 83 100 F 4.17 Acidity, meq./100 g 0.35 SMS 199/62. Asphaltenes, percent by weight: EMS 6B2.

Isopentane insolubles 1. 61 Benzene insolnbles 0. 04 FIA, percent by volume:

Saturates 30 Olefins Aromatics 7 Sulfur, percent by weight:

Elemental (polarographie) H 0.023 (0.81) Anal. Chem., 24,

1, 745 (1952). Elemental (electrometric) a 0.022 (0.72) SMS 177. Mereaptan SMS 177. Total B 0.66 (1.41) EMS 184/62 Grav.

' After saturating with S0 at 23 0.

TABLE B Asphaltene content of fresh and recycle recovered carriers Asphaltenes, percent wt.

Determined by precipitation with 10 vol. isopentane/vol. oil followed by centrifugation, decantation, washing with the same amount of isopentane, and drying in a vacuum oven in the centrifuge tube (De Laval Gyrotester). 12 0(5i6s separated from sulfur slurries by centrifugation at TABLE 1.SULFUR SLURRY PREPARATIONMOLTEN SULFUR SPRAYED INTO CRUDE OIL [Evaporative cooling of slurry with butane. Mixing vessel: -gallon autoclave, ID, 4 bladed turbine impeller. Crude oil: 8:6

Medicine River/Innisfail blend. Oil feed temperature 2224 0. Shell Canada Ltd. sulfur] Run No.

Oil rate, lbJhr 161 161 81 161 161 1 161 1 161 1 161 1 161 1 156 161 161 310 89 Sulfur rate, lbJhr- 148 144 73 144 148 145 149 150 145 140 142 143 242 74 Sulfur nozzle temp. C 143 138 150 145 143 144 146 144 144 145 138 145 141 144 Butane rate, ill hr.-. 18 16 9 16 16 17 16 18 18 19 19 17 33 10 Mixing vessel pressure, p.s.i.g. 20 18 20 16 17 18 18 20 21 20 19 35 16 18 Agitator speed, r.p.m 465 465 430 430 430 430 780 780 780 780 430 430 430 430 Weight-median particle size, 2 dao, u. 70 95 145 270 660 650 630 560 480 630 210 35 50 330 Finer than 325 mesh, percent by weight... 26 12 8. 3 2. 4 0. 5 0. 2 0. 4 0.4 0. 3 0. 4 1. 9 62 43 0. 9

1 Oil feed contained 40 percent by weight settled oil from previous run to simulate recycle operation.

2 Determined by wet screen analysis.

TABLE 2.MOLTEN SULFUR SPRAYED INTO CRUDE OIL [Evaporative cooling of slurry with butane. Mixing vessel: 5-gall0n autoclave, 10" ID, 4-bladed turbine impeller. Crude oil: Interprovincial Mix (IPM)] Run No.

Oil rate, lbJhr 161 88 161 161 116 161 650 630 327 317 v 680 680 347 Sulfur rate, lb. hr 150 80 146 148 150 149 574 577 288 288 609 609 310 Sulfur nozzle diameter, in 0.067 0.067 0.039 0. 125 0. 067 0.067 O. 250 0.250 0.250 0.250 0. 375 0.375 0.375 Sulfur jet velocity, f.p.s 15. 3 8. 2 44 4. 3 15. 3 15.3 4. 2 4. 2 2. 1 2. 1 2. 0 2.0 1.0 Sulfur nozzle temp, C. 146 146 147 147 146 147 152 153 150 153 151 1 145 153 Butane rate, lb./hr 20 11 19 20 23 31 58 2 64 60 60 2 64 2 6O 2 Mixing vessel temp., C. r 60 60 60 60 62 66 60 60 57 60 60 60 Mixing vessel pressure, 22 21 22 23 22 35 26 16 31 3O 15 I5 23 Agitor speed, r.p.m 430 430 430 730 730 430 730 730 730 430 730 730 730 Slurry residence time, 6. 6 13 6.6 6. 6 7. 8 6.6 1. 7 1. 8 3. 2 3. 2 1. 7 1. 7 3. 2 Slurry density, gJml 3 1.12 1.12 1.11 1.12 1.16 1.09 1.12 1.13 1.09 1.09 1.13 1. 04 1.12 Slurry concentration, percent by volume S 24. 6 24. 0 24.3 24.4 29. 3 22. 9 24.4 24. 7 22. 4 22. 8 24.5 24. 7 24.0 Wcightmedian particle size, (150, a. 210 330 560 240 200 570 400 650 780 490 770 630 Finer than 325 mesh, percent by weight 2. 2 1.0 32 1.0 2. 4 3. 2 0. 9 1. 1 1. 8 1. 3 1. 6 1. 3 1. 8

1 Nozzle not submerged; temperature variable. 2 Butane venting required to maintain 60 C. 1 Calculated from feed rates.

4 Determined by wet screen analysis.

TABLE 3.SULFUR SLURRY PREPARAT10NMOLTEN SULFUR SPRAYED INTO CRUDE OIL [Evaporative cooling of slurry with butane. lliixing vessel: gallon autoclave, ID, 4-bladed turbine impeller, 680 r.p.m. Crude oil: 1PM] Run No.

Oil rate, lb./hr 635 870 690 555 290 79 168 71 154 73 145 75 115 28 Sulfur rate, lb./hr 390 387 390 516 255 72 158 63 147 67 138 67 100 26 Sulfur nozzle diameter, in 0. 067 0. 067 0. 067 0. 125 0. 125 0. 125 0.375 0. 067 O. 250 0. 039 O. 039 O. 039 0. 107 0. 126 Sulfur jet velocity, f.p.s 39. 8 39. 5 39. 7 15. 0 7. 4 2. 1 0. 51 6. 4 1. 1 2O 41. 4 20. 2 4. 0 7. 6 Sulfur nozzle temperatur 157 151 151 153 151 144 150 155 148 150 153 152 152 155 Butane rate, lb./hr 20 O 38 63 35 16 27 16 34 15 28 14 20 36 Mixing vessel temperature, C 58 56 60 61 6O 60 60 60 60 60 60 60 60 60 Mixing vessel pressure, p.s.i.g.. 12 4 16 15 17 16 28 24 18 24 22 22 21 18 Slurry residence time, mi 2.6 1. 7 1. 9 2.0 3. 8 13 6. 2 14 6. 4 14 7.0 14 9. 2 3. 8 Slurry density, g./ml. 1. 08 1.03 1. 05 1.13 1.11 1.08 1.10 1. 06 1. 09 1.07 1.09 1.08 1.08 1.12 Slurry concentration, percent by volume S 2 18. 5 14. 6 16. 8 23.6 22. 4 21. 6 23. 8 20.7 21.4 22. 5 23.3 22. 4 22.1 23.1 Weight-median particle size, d 1 50 55 160 490 650 670 400 700 190 70 130 640 400 Finer than 325 mesh, percent by weight 41 52 34 6. 6 2. 6 2. 5 2.4 2. 3 1.8 3. 7 31 8. 4 2.1 2. 4

1 Calculated from feed rates. 2 Determined from wet screen analysis.

TABLE 4.-SULFUR SLURRY PREPARATIOgIi-LMOLTEN SULFUR SPRAYED INTO CRUDE [Evaporative cooling with added butane. Mixing vessel: 5gallon autoclave, 10" ID, 4 bladed turbine impeller, 680 r.p.m. Crude oil: Rangeland-type crude] Run No.

on rate, 1b./hr 158 155 174 171 166 164 125 Sulfur rate, lb./hr 158 157 150 153 136 96 93 Sulfur nozzle diameter, in 0. 067 0. 067 0.067 0.067 0. 086 0.086 0.086 Sulfur jet velocity, i.p.s 16. 1 16.0 15. 3 15.6 8. 4 5. 9 5. 7 Sulfur nozzle temperature, C. 150 151 151 150 151 149 149 Butane rate, lb./hr 25 29 29 29 28 26 25 Mixing Vessel temperature, C. 60 61 62 61 62 61 60 Mixing vessel pressure, p.s.i.g 24 24 23 24 25 25 24 Slurry residence time, min)- 6. 8 6. 9 6.0 6.0 6.7 7. 3 8. 8 Slurry density, g./m1. 3 1.19 1.12 1.16 1.17 1.14 1.07 1.11 Slurry concentration, percent by volume S 2 29 29 26 27 25 19 23 Weight-median particle size, (150, 1 4 160 125 150 145 200 330 360 Finer than 325 mesh, percent by weight 3. 8 16 15 13 7. 5 3. 5 3. 6

1 Interprovincial Mix (1PM) crude oil. 2 Calculated from feed rates. 3 Assuming all added butane weathered off. 4 Determined from wet screen analysis.

Sulfur slurries prepared by the method of the present (c) conducting the partially cooled sulfur slurry to a invention can be transported through pipelines over great 40 flasher vessel where the remainder of the low molecudistances without the danger of sulfur deposition, agglomlar weight hydrocarbon is removed and evaporation eration, sticking or plugging of the pipelines. cooling and thickening the sulfur slurry to a sulfur At the terminal end of the line the sulfur can be recontent of above about 20% by Weight; and, moved from the liquid hydrocarbon by suitable means (d) injecting the thickened and cooled sulfur slurry such as described in US. Pat. No. 2,809,885 or as deinto a pipeline. scribed in the copending patent application Ser. No. 684,- 4 2. The method of claim 1 wherein the carrier in (a) is 507, filed Nov. 20, 1967 which comprises treating oil cona liquid petroleum selected from the group consisting of taminated sulfur with an aqueous solution containing a petroleum distillates, petroleum condensates, crude oil and mixture of alkali hydrosulfide and corresponding hydroxmixtures thereof to which is added a small amount of a ide, e.g., ammonium hydrosulfide and ammonium hysurfactant naturally present in crude oil. droxide or by other suitable means such as sulfur can be 3. The method of claim 2 wherein the carrier in (a) is recovered from the oil slurry by filtration of molten sula crude oil and the surfactant is an asphaltenic hydrocarfur and liquid-liquid extraction with a hydrocarbon solbon. vent containing 10-50% aromatic. Thus, at the receiving 4. The method of claim 1 wherein the carrier (a) is a terminal the sulfur slurry can be filtered and washed. The crude oil containing asphaltenes and the evaporating coolrecovered sulfur is then melted and purified by liquiding liquid (b) is butane and the thickened sulfur slurry liquid extraction with an aromatic hydrocarbon such as of (c) contains from 20 to 35% sulfur by Weight. cumene. Also, if desired, the filtered sulfur can be steam 5. T he method of claim 4 wherein the thickened sulfurstripped to recover bright yellow sulfur. asphaltene-containing crude oil slurry is essentially free The foregoing description of the invention is merely mf butane. tended to be explanatory thereof. Various changes in the details of the described method may be made within the References Cited scope of the appended claims without departing from the UNITED STATES PATENTS spirit of the invention.

We claim as our invention: 2,798,772 7/1957 Re y 302-44 1. A method of transporting cooled sulfur slurries 65 2,917,345 12/1959 Phillips ell 30214 through a pipeline to a terminal station comprising: 2,947,578 8/1960 Corneil et al. 302-14 (a) injecting molten sulfur into a liquid petroleum 3,368,876 2/ 1968 Bailey 302-14 carrier having a viscosity above liquefied petroleum 3,432,209 3/ 1969 Scott 302 -66 gas containing a small amount of volatilizable low 3,443,837 5/ 1959 Meyer r 1 302 14 molecular Weight hydrocarbon of less than 6 carbon 70 3,47 ,441 11 19 9 Elliott 0 atoms under pressure to form a sulfur slurry containing at least 10% sulfur by volume; ANDRES H. NIELSEN, Primary Examiner (b) partially evaporating the low molecular weight hydrocarbon to partially cool the slurry and to concen- US. Cl. X.R. trate the sulfur in the slurry to at least 15% by weight; 302-14 

